YANGON (Reuters) - Two Reuters reporters accused in Myanmar of possessing secret documents were subjected to sleep deprivation and asked if they were "spies" during police interrogations, their lawyers suggested during questions posed to a police witness on Monday.

Cross-examining Police Captain Myint Lwin at a court in Yangon, defense lawyer Than Zaw Aung asked if he was aware the two reporters were "not allowed to sleep" for three consecutive days during the initial police probe after their detention on Dec. 12.

He also asked the witness whether reporter Kway Soe Oo was "forced to kneel down" on the floor for more than three hours during questioning by investigators.

In what has become a landmark press freedom case, the court in Yangon has been holding hearings since January to decide whether Kyaw Soe Oo, 28, and his Reuters colleague Wa Lone, 32, will be charged under the colonial-era Official Secrets Act. The alleged offences carry a maximum penalty of 14 years in prison.

Captain Myint Lwin, the officer in charge of the Yangon police station that conducted the preliminary inquiry after the pair were arrested, denied the reporters were deprived of sleep or made to kneel, saying officers were not allowed to "do such a thing" under his command.

He also denied, under cross-examination, that the reporters were sent to a specialist interrogation facility after their arrests, saying they were detained at the police station in northern Yangon until his team finalised the preliminary probe and handed the case to a police crime investigation unit on Dec. 26.

After the hearing, Wa Lone and Kyaw Soe Oo confirmed details of their treatment, telling reporters they had been questioned every two hours for about three days after their arrests by different officers, who asked if they were "spies".

Wa Lone said it was "completely untrue" that they had remained in a regular police station.

"It is mental and physical torture," a second defense lawyer, Khin Maung Zaw, told Reuters after Monday's proceedings, adding that evidence gathered through such methods was unlawful and should not be presented to the court.

Prosecutor Kyaw Min Aung declined to comment at the end of the hearing.

Police spokesman Myo Thu Soe, contacted by telephone, said he was not aware of the matter and declined to comment.

Myanmar government spokesman Zaw Htay was not immediately available for comment after Monday's hearing. Previously, he has declined to comment on the case or the conduct of the investigation, saying Myanmar's courts are independent and the case would be conducted according to the law.

"DEEPLY CONCERNED"

Reuters President and Editor-in-Chief Stephen J. Adler said in a statement the news agency had long been deeply concerned about how the reporters were treated during their interrogation.

"No one, including Wa Lone and Kyaw Soe Oo, should be subject to mistreatment of the kind they describe," he said.

"It is for this reason, and many others, that we hope the court will bring this matter to an end as swiftly as possible, and restore the press's confidence in its ability to work safely and responsibly in Myanmar."

At the time of their arrest, the reporters had been working on an investigation into the killing of 10 Rohingya Muslim men and boys in a village in western Myanmar's Rakhine state. The killings took place during a military crackdown that United Nations agencies say sent nearly 700,000 people fleeing to Bangladesh.

The reporters have told relatives they were arrested almost immediately after being handed some rolled up papers at a restaurant in northern Yangon by two policemen they had not met before, having been invited to meet the officers for dinner.

After the hearing, Kyaw Soe Oo, in handcuffs, told reporters that he was made to kneel on the floor for "three to four hours" when he refused to give the address of a hotel where he had been staying in Yangon or divulge details of the Reuters investigation.

Global advocates for press freedom, human rights activists, as well the United Nations and several Western countries, have called for the release of the Reuters journalists.

On Monday, diplomats from the European Union and France - as well as others - observed the proceedings.